RE: adaptive cursor sharing and bind peeking
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <Christian.Antognini@xxxxxxxxxxxx>, "'Carlos Sierra'" <carlos.sierra.usa@xxxxxxxxx>
- Date: Fri, 31 May 2013 13:37:27 -0400
In the context given, I *think* the open cursor operation is effectively
what Carlos includes as one of the possibilities of an execution in his
reference to "every execution" (as opposed to each fetch from an open
cursor).
Please straighten me out on this if I'm misunderstanding.
Regards,
mwf
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Christian Antognini
Sent: Friday, May 31, 2013 3:06 AM
To: Carlos Sierra
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: adaptive cursor sharing and bind peeking
Hi Carlos
> Once it is bind aware on every execution it looks at the values of
> binds and compares to acs selectivity profile for this sql
When a cursor is open, its execution plan cannot be changed. As a result,
the peeking and everything else that goes with it in case of a bind-aware
cursor can only be done when a parse call is performed. This is also the
reason why static cursors in PL/SQL loops or Java applications using
client-side statement caching cannot take advantage of ACS.
HTH
Chris Antognini
Troubleshooting Oracle Performance, Apress 2008 http://top.antognini.ch
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